Skeletal Radiol DOI 10.1007/s00256-015-2125-5
CASE REPORT
Disruption of the proximal tibiofibular joint in the setting of multi-ligament knee injury Jack A. Porrino
Received: 28 November 2014 / Revised: 23 January 2015 / Accepted: 18 February 2015 # ISS 2015
Abstract Instability of the proximal tibiofibular joint is a relatively uncommon condition when in isolation; however, instability of the proximal tibiofibular joint is far more frequent in those presenting with a severe multi-ligament injury of the knee. If this joint is left unstable, repair of a co-existent injury of the posterolateral corner may fail, regardless of the proficiency of the technique. We present two patients with disruption of the proximal tibiofibular joint, including the MRI appearance, who initially presented to our hospital for management of significant polytrauma, as well as multi-ligament injury of the ipsilateral knee.
unrecognized, proximal tibiofibular joint instability might lead to failure or persistent instability of a posterolateral corner repair/reconstruction [1]. We describe the clinical presentation and imaging findings, including the MRI appearance, of disruption of the proximal tibiofibular joint in two patients who initially presented to our institution for management of significant polytrauma, including multi-ligament injury of the ipsilateral knee, in an effort to draw the radiologist’s attention to this easily overlooked injury.
Case reports Keywords Proximal tibiofibular joint . Instability . Multi-ligament knee injury . Imaging appearance
Introduction Isolated injury to the proximal tibiofibular joint is a relatively rare entity [1–4]. However, Jabara et al. recently reported a dislocated or dislocatable proximal tibiofibular joint in 9 % of those encountered with a multi-ligament knee injury (defined as a radiographic knee dislocation or grade 3 instability of two or more ligamentous structures; combined anterior cruciate and medial collateral ligament injuries were not included in the cohort) [1]. The authors cautioned that if left
J. A. Porrino (*) Department of Radiology, University of Washington, 4245 Roosevelt Way NE, Box 354755, Seattle, WA 98105, USA e-mail: [email protected]
Case 1 A 43-year-old man with no significant past medical history was traveling to work by motorcycle at 60 miles per hour when a car Bsideswiped^ him, at which point he fell down below his motorcycle onto his right lower extremity. The patient was helmeted, and incurred no head trauma. He was taken to a local hospital for initial evaluation, and then transferred to our institution for further management given the nature of his injuries. Initial radiograph and CT imaging (Figs. 1, 2) of the right lower extremity demonstrated right knee subluxation, open patella fracture, comminuted medial tibial plateau fracture, comminuted proximal fibular shaft fracture, and marked proximal tibiofibular joint dislocation. The patient was hemodynamically stable upon presentation. The vascular status of his right lower extremity was intact, as confirmed by intact peripheral pulses, normal ankle–brachial indices upon presentation, and serial neurovascular examinations. He reported severe pain in the right lower extremity, with no numbness or paresthesia.
Skeletal Radiol
was obvious widening of the joint space, moderate fluid within the joint space, and no definable ligamentous capsule at the proximal tibiofibular joint. Edema was present within the tibia at the level of the proximal tibiofibular joint. All injuries identified on MRI were confirmed intraoperatively. The proximal tibiofibular joint was reduced and held with a Kirschner wire of 2 mm in diameter. One 3.5mm cortical screw with a washer was then used to transfix the proximal tibiofibular joint (Fig. 4). Arthroscopic anterior cruciate ligament reconstruction using a hamstring graft from the left leg, mini-openassisted reattachment of the posterior cruciate ligament to its femoral origin, open repair of the superficial and deep components of the medial collateral ligament, open repair of fibular collateral ligament and lateral capsular avulsion injuries, and debridement with partial medial meniscectomy were also performed.
Case 2 Fig. 1 Case 1: a 43-year-old man with proximal tibiofibular joint disruption in the setting of multi-ligament knee injury. a Frontal, b oblique, and c lateral radiographs demonstrate subluxation of the tibiofemoral/knee joint, in addition to widening of the proximal tibiofibular joint. There are fractures of the patella and tibial plateau
A preoperative MRI of the right knee (Fig. 3) was obtained on hospital day 4. In addition to the aforementioned osseous injuries, the MRI revealed a complete tear of the anterior cruciate ligament, complete proximal avulsion of the posterior cruciate ligament, complete distal avulsion of the medial collateral ligament, complete tear of the proximal fibular collateral ligament, lateral capsular avulsion, and tear of the medial meniscus. With regard to the proximal tibiofibular joint, there
Fig. 2 Case 1. a Axial and b coronal CT images demonstrate widening of the proximal tibiofibular joint (arrows)
A 19-year-old woman with no significant past medical history was the driver in a rollover motor vehicle crash in which she was ejected from the vehicle approximately 50 feet. The patient was hemodynamically unstable in the field and resuscitated with intravenous fluids and blood products. She was taken to the operating room for an exploratory laparotomy following a positive focused assessment with sonography in trauma (FAST) examination upon presentation. Splenectomy was performed owing to splenic laceration, and a left flankpenetrating soft tissue defect was repaired. The orthopedic surgery service assisted for irrigation and debridement of an open fracture of the left iliac wing. Additional abnormalities identified on imaging included open fracture–dislocation of the left ankle, fractures of the right radius and ulna, degloving injury of
Skeletal Radiol Fig. 3 Case 1. a Axial T2 fatsuppressed, b sagittal T2 fatsuppressed, and c coronal proton density fat-suppressed MR images of the affected knee demonstrate widening of the proximal tibiofibular joint (arrows) with fluid at the joint space (curved arrow) and no defined ligamentous proximal tibiofibular joint capsule. Ffibular head
the left thigh, right hepatic lobe laceration, left renal laceration, left adrenal hematoma, pulmonary contusion, right 10–12 rib fractures, penetrating labial injury, and a C2 vertebral body fracture.
Fig. 4 Case 1. The postoperative frontal radiograph demonstrates restoration of alignment of the proximal tibiofibular joint with a single cortical screw fixing the joint (straight arrow). Additional hardware related to patella and fibular fracture fixation, as well as ligamentous and capsule repair is present
Left knee radiographs were acquired on hospital day 5 because of the presence of knee laxity on physical examination suspicious for multi-ligament knee injury, and appropriately interpreted as normal (Fig. 5). Notably, there was no appreciable widening of the proximal tibiofibular joint. Approximately 2 weeks into the hospital course, an MRI of the left knee (Fig. 6) was
Fig. 5 Case 2: a 19-year-old woman with proximal tibiofibular joint disruption in the setting of a multi-ligament knee injury. a Frontal and b lateral radiographs demonstrate a normal appearance of the proximal tibiofibular joint
Skeletal Radiol Fig. 6 Case 2. a, b Axial T2 fatsuppressed and c sagittal proton density MR images of the affected knee demonstrate disruption of the anterior ligamentous capsule of the proximal tibiofibular joint (straight arrow), but an intact posterior ligamentous capsule (curved arrow) and a normal proximal tibiofibular joint relationship. There is abnormal fluid at the joint space. d Coronal proton density fat-suppressed MR image demonstrates apparent discontinuity of the proximal fibular collateral ligament (arrow), corresponding to a partial-thickness tear/contusion intraoperatively
performed. This demonstrated disruption of the anterior proximal tibiofibular ligamentous capsule with increased fluid within the tibiofibular joint space, but without concomitant widening of the joint. The posterior ligamentous capsule was intact. The proximal tibiofibular joint was repaired approximately 3 weeks after admission with a single cortical screw. Additional injuries on this MRI included partial thickness tear of the anterior cruciate ligament, highgrade partial thickness tear of the proximal fibular collateral ligament, partial avulsion of the distal popliteus tendon at the hiatus, and rupture of the medial and lateral patellar retinacular attachments. Intraoperatively, the fibular collateral ligament was contused and irregular at its proximal origin; however, it was grossly intact. The popliteus tendon was reattached to the femur with a suture anchor. Injuries involving the retinacular attachments and anterior cruciate ligament were not addressed surgically.
Discussion The proximal tibiofibular joint is a synovial joint lined by hyaline articular cartilage that communicates with the knee joint in 10–60 % of the population. A thick joint
capsule, strengthened by anterior (three divisions) and posterior (two divisions) ligamentous attachments, connecting the proximal fibula to the tibia, provide stability. The normal and intact ligamentous capsule appears universally hypointense on all MR pulse sequences, with the individual aforementioned divisions described to be difficult to separate. Additional support is provided anteriorly by the biceps femoris tendon insertion onto the fibular head, posteriorly by the popliteus tendon, superiorly by the fibular collateral ligament, and inferiorly by the interosseous membrane (Fig. 7). A small amount of fluid within the joint may normally be present [1–5]. Instability of the proximal tibiofibular joint is a relatively rare isolated injury of the knee [1–4]. However, the injury is more commonly seen when in combination with other osseous or ligamentous pathological conditions [1, 4]. Proximal tibiofibular joint dislocation usually results from a severe twisting motion of the flexed knee. This joint serves to reduce rotational stress that is applied at the ankle, dissipate lateral tibial bending moments, and transfer axial loads while standing [2, 3]. Injuries to this joint have been classified in the past by Lyle (1925), Harrison and Hindenach (1959), and
Skeletal Radiol
Fig. 7 Anatomy of the proximal tibiofibular joint in a the anterior and b the posterior projections
Ogden (1974). Ogden divided the normal proximal tibiofibular joint into one of two types: an oblique type (greater than 20 ° horizontal joint inclination relative to the horizontal plane) and a horizontal type (less than 20 ° horizontal joint inclination relative to the horizontal plane) type. Ogden reported that the horizontal type has inherently more rotational mobility with a larger surface area than its oblique counterpart, and therefore increased resistance against rotational forces [2–4]. The most common form of proximal tibiofibular joint dislocation is anterolateral dislocation, occurring with inversion and plantar flexion of the foot. This mechanism results in tension on the peroneal muscles, extensor digitorum longus, and extensor hallucis longus, and an
eventual forward dislocating force on the proximal fibula [2, 4]. Rotational movements on the joint occur during this ankle motion, while the knee is flexed, as this flexion relaxes the biceps femoris tendon and fibular collateral ligament [2–4]. Injury of the proximal tibiofibular joint can result in chronic lateral knee pain and fibular (peroneal) nerve palsy with potential drop foot when left undiagnosed. When this injury occurs in isolation, management ranges from closed reduction and immobilization to fixation with Kirschner wires or screws. When the diagnosis is delayed, and reduction can no longer be achieved, options include resection of the fibular head, arthrodesis of the joint, or reconstruction with tendon graft [2–4, 6]. When the injury occurs in the setting of a multiligament knee injury, numerous methods exist for stabilization and/or reconstruction of the proximal tibiofibular joint, including direct repair, reconstruction of the supporting ligaments with split biceps femoris tendon, single cortical screw fixation (utilized in both cases in our report), and various screw–pin constructs [1]. If subtle, proximal tibiofibular dislocation can be missed on routine radiographs of the affected knee, even when clinical suspicion is present [2]. In case 2, there was no demonstrable widening of the proximal tibiofibular joint on the radiographs. Obtaining comparison radiographs of the contralateral knee, or bilateral CT in an effort to detect asymmetry can improve diagnostic efficacy, but requires a pre-existing clinical suspicion [3, 4]. Additionally, a lateral radiograph is essential during the work-up, in that incongruity of the joint may only be apparent on this view [2]. In the setting of multi-ligament knee injury, disruption of the proximal tibiofibular joint is not uncommon [1]; however, the clinical examination may be complicated by extensive soft tissue injury and multiple fractures, as in our cases. As such, MRI may be the lone opportunity for the radiologist to make this diagnosis. Disruption of this joint is an important co-existing injury to recognize in the setting of the multi-ligament knee injury, as proximal tibiofibular joint integrity is necessary for performing a fibular head-based posterolateral corner knee reconstruction, and if left unrecognized, proximal tibiofibular joint instability may lead to failure or persistent instability of a posterolateral corner repair/reconstruction [1]. Our two cases demonstrate the imaging appearance of proximal tibiofibular joint instability in the setting of a complex multi-ligament knee injury, when radiographically obvious and when radiographically occult, highlighting the MRI findings. We urge the radiologist to pay close attention to this joint in the setting of a multi-ligament knee injury.
Skeletal Radiol Conflict of interest No conflict of interest.
References 1. Jabara M, Bradley J, Merrick M. Is stability of the proximal tibiofibular joint important in the multiligament-injured knee? Clin Orthop Relat Res. 2014;472(9):2691–7. 2. Ahmad R, Case R. Dislocation of the fibular head in an unusual sports injury: a case report. J Med Case Rep. 2008;2:158.
3. Milankov M, Kecojević V, Gvozdenović N, Obradović M. Dislocation of the proximal tibiofibular joint. Med Pregl. 2013;66(9–10):387–91. 4. Sekiya JK, Kuhn JE. Instability of the proximal tibiofibular joint. J Am Acad Orthop Surg. 2003;11(2):120–8. 5. Forster BB, Lee JS, Kelly S, et al. Proximal tibiofibular joint: an oftenforgotten cause of lateral knee pain. AJR Am J Roentgenol. 2007;188(4):W359–66. 6. Shelbourne KD, Pierce RO, Ritter MA. Superior dislocation of the fibular head associated with a tibia fracture. Clin Orthop Relat Res. 1981;(160):172–4.
CASE REPORT
Disruption of the proximal tibiofibular joint in the setting of multi-ligament knee injury Jack A. Porrino
Received: 28 November 2014 / Revised: 23 January 2015 / Accepted: 18 February 2015 # ISS 2015
Abstract Instability of the proximal tibiofibular joint is a relatively uncommon condition when in isolation; however, instability of the proximal tibiofibular joint is far more frequent in those presenting with a severe multi-ligament injury of the knee. If this joint is left unstable, repair of a co-existent injury of the posterolateral corner may fail, regardless of the proficiency of the technique. We present two patients with disruption of the proximal tibiofibular joint, including the MRI appearance, who initially presented to our hospital for management of significant polytrauma, as well as multi-ligament injury of the ipsilateral knee.
unrecognized, proximal tibiofibular joint instability might lead to failure or persistent instability of a posterolateral corner repair/reconstruction [1]. We describe the clinical presentation and imaging findings, including the MRI appearance, of disruption of the proximal tibiofibular joint in two patients who initially presented to our institution for management of significant polytrauma, including multi-ligament injury of the ipsilateral knee, in an effort to draw the radiologist’s attention to this easily overlooked injury.
Case reports Keywords Proximal tibiofibular joint . Instability . Multi-ligament knee injury . Imaging appearance
Introduction Isolated injury to the proximal tibiofibular joint is a relatively rare entity [1–4]. However, Jabara et al. recently reported a dislocated or dislocatable proximal tibiofibular joint in 9 % of those encountered with a multi-ligament knee injury (defined as a radiographic knee dislocation or grade 3 instability of two or more ligamentous structures; combined anterior cruciate and medial collateral ligament injuries were not included in the cohort) [1]. The authors cautioned that if left
J. A. Porrino (*) Department of Radiology, University of Washington, 4245 Roosevelt Way NE, Box 354755, Seattle, WA 98105, USA e-mail: [email protected]
Case 1 A 43-year-old man with no significant past medical history was traveling to work by motorcycle at 60 miles per hour when a car Bsideswiped^ him, at which point he fell down below his motorcycle onto his right lower extremity. The patient was helmeted, and incurred no head trauma. He was taken to a local hospital for initial evaluation, and then transferred to our institution for further management given the nature of his injuries. Initial radiograph and CT imaging (Figs. 1, 2) of the right lower extremity demonstrated right knee subluxation, open patella fracture, comminuted medial tibial plateau fracture, comminuted proximal fibular shaft fracture, and marked proximal tibiofibular joint dislocation. The patient was hemodynamically stable upon presentation. The vascular status of his right lower extremity was intact, as confirmed by intact peripheral pulses, normal ankle–brachial indices upon presentation, and serial neurovascular examinations. He reported severe pain in the right lower extremity, with no numbness or paresthesia.
Skeletal Radiol
was obvious widening of the joint space, moderate fluid within the joint space, and no definable ligamentous capsule at the proximal tibiofibular joint. Edema was present within the tibia at the level of the proximal tibiofibular joint. All injuries identified on MRI were confirmed intraoperatively. The proximal tibiofibular joint was reduced and held with a Kirschner wire of 2 mm in diameter. One 3.5mm cortical screw with a washer was then used to transfix the proximal tibiofibular joint (Fig. 4). Arthroscopic anterior cruciate ligament reconstruction using a hamstring graft from the left leg, mini-openassisted reattachment of the posterior cruciate ligament to its femoral origin, open repair of the superficial and deep components of the medial collateral ligament, open repair of fibular collateral ligament and lateral capsular avulsion injuries, and debridement with partial medial meniscectomy were also performed.
Case 2 Fig. 1 Case 1: a 43-year-old man with proximal tibiofibular joint disruption in the setting of multi-ligament knee injury. a Frontal, b oblique, and c lateral radiographs demonstrate subluxation of the tibiofemoral/knee joint, in addition to widening of the proximal tibiofibular joint. There are fractures of the patella and tibial plateau
A preoperative MRI of the right knee (Fig. 3) was obtained on hospital day 4. In addition to the aforementioned osseous injuries, the MRI revealed a complete tear of the anterior cruciate ligament, complete proximal avulsion of the posterior cruciate ligament, complete distal avulsion of the medial collateral ligament, complete tear of the proximal fibular collateral ligament, lateral capsular avulsion, and tear of the medial meniscus. With regard to the proximal tibiofibular joint, there
Fig. 2 Case 1. a Axial and b coronal CT images demonstrate widening of the proximal tibiofibular joint (arrows)
A 19-year-old woman with no significant past medical history was the driver in a rollover motor vehicle crash in which she was ejected from the vehicle approximately 50 feet. The patient was hemodynamically unstable in the field and resuscitated with intravenous fluids and blood products. She was taken to the operating room for an exploratory laparotomy following a positive focused assessment with sonography in trauma (FAST) examination upon presentation. Splenectomy was performed owing to splenic laceration, and a left flankpenetrating soft tissue defect was repaired. The orthopedic surgery service assisted for irrigation and debridement of an open fracture of the left iliac wing. Additional abnormalities identified on imaging included open fracture–dislocation of the left ankle, fractures of the right radius and ulna, degloving injury of
Skeletal Radiol Fig. 3 Case 1. a Axial T2 fatsuppressed, b sagittal T2 fatsuppressed, and c coronal proton density fat-suppressed MR images of the affected knee demonstrate widening of the proximal tibiofibular joint (arrows) with fluid at the joint space (curved arrow) and no defined ligamentous proximal tibiofibular joint capsule. Ffibular head
the left thigh, right hepatic lobe laceration, left renal laceration, left adrenal hematoma, pulmonary contusion, right 10–12 rib fractures, penetrating labial injury, and a C2 vertebral body fracture.
Fig. 4 Case 1. The postoperative frontal radiograph demonstrates restoration of alignment of the proximal tibiofibular joint with a single cortical screw fixing the joint (straight arrow). Additional hardware related to patella and fibular fracture fixation, as well as ligamentous and capsule repair is present
Left knee radiographs were acquired on hospital day 5 because of the presence of knee laxity on physical examination suspicious for multi-ligament knee injury, and appropriately interpreted as normal (Fig. 5). Notably, there was no appreciable widening of the proximal tibiofibular joint. Approximately 2 weeks into the hospital course, an MRI of the left knee (Fig. 6) was
Fig. 5 Case 2: a 19-year-old woman with proximal tibiofibular joint disruption in the setting of a multi-ligament knee injury. a Frontal and b lateral radiographs demonstrate a normal appearance of the proximal tibiofibular joint
Skeletal Radiol Fig. 6 Case 2. a, b Axial T2 fatsuppressed and c sagittal proton density MR images of the affected knee demonstrate disruption of the anterior ligamentous capsule of the proximal tibiofibular joint (straight arrow), but an intact posterior ligamentous capsule (curved arrow) and a normal proximal tibiofibular joint relationship. There is abnormal fluid at the joint space. d Coronal proton density fat-suppressed MR image demonstrates apparent discontinuity of the proximal fibular collateral ligament (arrow), corresponding to a partial-thickness tear/contusion intraoperatively
performed. This demonstrated disruption of the anterior proximal tibiofibular ligamentous capsule with increased fluid within the tibiofibular joint space, but without concomitant widening of the joint. The posterior ligamentous capsule was intact. The proximal tibiofibular joint was repaired approximately 3 weeks after admission with a single cortical screw. Additional injuries on this MRI included partial thickness tear of the anterior cruciate ligament, highgrade partial thickness tear of the proximal fibular collateral ligament, partial avulsion of the distal popliteus tendon at the hiatus, and rupture of the medial and lateral patellar retinacular attachments. Intraoperatively, the fibular collateral ligament was contused and irregular at its proximal origin; however, it was grossly intact. The popliteus tendon was reattached to the femur with a suture anchor. Injuries involving the retinacular attachments and anterior cruciate ligament were not addressed surgically.
Discussion The proximal tibiofibular joint is a synovial joint lined by hyaline articular cartilage that communicates with the knee joint in 10–60 % of the population. A thick joint
capsule, strengthened by anterior (three divisions) and posterior (two divisions) ligamentous attachments, connecting the proximal fibula to the tibia, provide stability. The normal and intact ligamentous capsule appears universally hypointense on all MR pulse sequences, with the individual aforementioned divisions described to be difficult to separate. Additional support is provided anteriorly by the biceps femoris tendon insertion onto the fibular head, posteriorly by the popliteus tendon, superiorly by the fibular collateral ligament, and inferiorly by the interosseous membrane (Fig. 7). A small amount of fluid within the joint may normally be present [1–5]. Instability of the proximal tibiofibular joint is a relatively rare isolated injury of the knee [1–4]. However, the injury is more commonly seen when in combination with other osseous or ligamentous pathological conditions [1, 4]. Proximal tibiofibular joint dislocation usually results from a severe twisting motion of the flexed knee. This joint serves to reduce rotational stress that is applied at the ankle, dissipate lateral tibial bending moments, and transfer axial loads while standing [2, 3]. Injuries to this joint have been classified in the past by Lyle (1925), Harrison and Hindenach (1959), and
Skeletal Radiol
Fig. 7 Anatomy of the proximal tibiofibular joint in a the anterior and b the posterior projections
Ogden (1974). Ogden divided the normal proximal tibiofibular joint into one of two types: an oblique type (greater than 20 ° horizontal joint inclination relative to the horizontal plane) and a horizontal type (less than 20 ° horizontal joint inclination relative to the horizontal plane) type. Ogden reported that the horizontal type has inherently more rotational mobility with a larger surface area than its oblique counterpart, and therefore increased resistance against rotational forces [2–4]. The most common form of proximal tibiofibular joint dislocation is anterolateral dislocation, occurring with inversion and plantar flexion of the foot. This mechanism results in tension on the peroneal muscles, extensor digitorum longus, and extensor hallucis longus, and an
eventual forward dislocating force on the proximal fibula [2, 4]. Rotational movements on the joint occur during this ankle motion, while the knee is flexed, as this flexion relaxes the biceps femoris tendon and fibular collateral ligament [2–4]. Injury of the proximal tibiofibular joint can result in chronic lateral knee pain and fibular (peroneal) nerve palsy with potential drop foot when left undiagnosed. When this injury occurs in isolation, management ranges from closed reduction and immobilization to fixation with Kirschner wires or screws. When the diagnosis is delayed, and reduction can no longer be achieved, options include resection of the fibular head, arthrodesis of the joint, or reconstruction with tendon graft [2–4, 6]. When the injury occurs in the setting of a multiligament knee injury, numerous methods exist for stabilization and/or reconstruction of the proximal tibiofibular joint, including direct repair, reconstruction of the supporting ligaments with split biceps femoris tendon, single cortical screw fixation (utilized in both cases in our report), and various screw–pin constructs [1]. If subtle, proximal tibiofibular dislocation can be missed on routine radiographs of the affected knee, even when clinical suspicion is present [2]. In case 2, there was no demonstrable widening of the proximal tibiofibular joint on the radiographs. Obtaining comparison radiographs of the contralateral knee, or bilateral CT in an effort to detect asymmetry can improve diagnostic efficacy, but requires a pre-existing clinical suspicion [3, 4]. Additionally, a lateral radiograph is essential during the work-up, in that incongruity of the joint may only be apparent on this view [2]. In the setting of multi-ligament knee injury, disruption of the proximal tibiofibular joint is not uncommon [1]; however, the clinical examination may be complicated by extensive soft tissue injury and multiple fractures, as in our cases. As such, MRI may be the lone opportunity for the radiologist to make this diagnosis. Disruption of this joint is an important co-existing injury to recognize in the setting of the multi-ligament knee injury, as proximal tibiofibular joint integrity is necessary for performing a fibular head-based posterolateral corner knee reconstruction, and if left unrecognized, proximal tibiofibular joint instability may lead to failure or persistent instability of a posterolateral corner repair/reconstruction [1]. Our two cases demonstrate the imaging appearance of proximal tibiofibular joint instability in the setting of a complex multi-ligament knee injury, when radiographically obvious and when radiographically occult, highlighting the MRI findings. We urge the radiologist to pay close attention to this joint in the setting of a multi-ligament knee injury.
Skeletal Radiol Conflict of interest No conflict of interest.
References 1. Jabara M, Bradley J, Merrick M. Is stability of the proximal tibiofibular joint important in the multiligament-injured knee? Clin Orthop Relat Res. 2014;472(9):2691–7. 2. Ahmad R, Case R. Dislocation of the fibular head in an unusual sports injury: a case report. J Med Case Rep. 2008;2:158.
3. Milankov M, Kecojević V, Gvozdenović N, Obradović M. Dislocation of the proximal tibiofibular joint. Med Pregl. 2013;66(9–10):387–91. 4. Sekiya JK, Kuhn JE. Instability of the proximal tibiofibular joint. J Am Acad Orthop Surg. 2003;11(2):120–8. 5. Forster BB, Lee JS, Kelly S, et al. Proximal tibiofibular joint: an oftenforgotten cause of lateral knee pain. AJR Am J Roentgenol. 2007;188(4):W359–66. 6. Shelbourne KD, Pierce RO, Ritter MA. Superior dislocation of the fibular head associated with a tibia fracture. Clin Orthop Relat Res. 1981;(160):172–4.
